Nowadays, there are various services for transmitting and/or receiving a message through portable devices, for instance, SMS, MMS, email service, and the like.
In a system for providing SMS and MMS services which are commonly used in this manner, there is no server for storing a user's message. Instead, if the user's terminal becomes in a situation that cannot receive a message such as power-off of the terminal, or the like, then a server in charge of transmitting the message temporarily stores the message. Then, if the user's terminal comes back to a situation that can receive a message, the temporarily stored message is transmitted. However, the server in charge of transmitting the message is not originally intended to store messages, and thus it stores the message only for a predetermined period of time and then deletes the message when the storage capacity becomes full. When the terminal requests the message to the server subsequent to the deletion, the server transmits an error message to the terminal.
On the other hand, in recent years, there have been attempts to integrate the foregoing various message services. One of those attempts is a Converged IP messaging (CPM) service.
The CPM service is a service in which the user can send and receive a CPM message in the environments of an IP multimedia subsystem. The CPM supports the environments of a pager mode message and a session mode message. Furthermore, the CPM service supports not only discrete media but also continuous media.
FIG. 1 is a block diagram illustrating the configuration of a network and a terminal for CPM services.
Referring to FIG. 1, there are illustrated a terminal 10, a SIP/IP network 50, a message storage server 60, an interworking server 70, and a CPM server 80.
First, the terminal 10 may include a message storage client 11 and a CPM client 12. The message storage client 11 stores transmitted and received messages, and synchronizes the stored messages with the message storage server 60.
The SIP/IP network 50 may be a network on the basis of IMS.
The message storage server 60 receives a message from the CPM server 80, and performs a role of storing transmitted and received messages and a conversation history with the media based on the users preference. Furthermore, the message storage server 60 may share data through synchronization with the terminal 10. In other words, the message storage server 60 receives and stores a message stored in the terminal 10, and transmits the message stored in the message storage server 60 to the terminal 10.
The message storage server 60 uses IMAP protocol for the synchronization. Accordingly, the message storage server 60 performs a role of an IMAP server, and the terminal 10 is operated as an IMAP client.
The interworking server 70 may include an interworking function unit 71 and an interworking selection function unit 72. The interworking function unit 71 performs a role of converting a CPM message into SMS, MMS, and the like, or converting SMS, MMS, and the like into a CPM message. The interworking selection function unit 72 performs a role of determining whether or not the conversion is performed.
The CPM server 80 may include a CPM participating function (PF) server 81 and a CPM controlling function (CF) server 82. The CPM PF server 81 transmits a message to the message storage server 60. Also, the CPM PF server 81 transmits and/or receives messages to and/or from the CPM client 12 of the terminal 10.
FIG. 2 is an exemplary view illustrating a process of transmitting and/or receiving CPM messages.
Referring to FIG. 2, there are illustrated a terminal A1 10A of a user A, terminals B1 and B2 10B of a user B, a home network of the user A, a home network of the user B, and a message storage server 60. The home network of the user A may include a SIP/IP network 50A and a CPM PF server 81A. The home network of the user B may include a SIP/IP network 50B and a CPM PF server 81B.
First, according to a request of the user A, the terminal A1 10A transmits a message to the CPM PF server 81A through the SIP/IP network 50A (S01, S02). The CPM PF server 81A transmits the message to the CPM PF server 81B through the SIP/IP network 50A within a home network of the user A and the SIP/IP network 50B in a home network of the user B (S03, S04, S05).
When receiving the message, the CPM PF server 81B transmits it to a terminal B1 10B of the user B though the SIP/IP network 50B (S06, S07).
Also, when receiving the message, the CPM PF server 81B transmits it to a terminal B2 10B of the user B though the SIP/IP network 50B (S08, S09).
The terminals B1 10B and B2 10B of the user B transmit OK messages respectively to the CPM PF server 81B through the SIP/IP network 50B within a home network of the user B (S10, S11).
When receiving the OK message, the CPM PF server 81B transmits it to the CPM PF server 81A of the user A through the SIP/IP network 50B within the home network of the user B and the SIP/IP network 50A within the home network of the user A (S12-S15).
When receiving the OK message, the CPM PF server 81A within the home network of the user A delivers the OK message to the terminal A1 10A that has transmitted the message (S16).
In the above, there has been described a process of delivering a message. Hereinafter, an example will be illustrated in which the transmitted and received message is stored in the message storage server 60.
FIG. 3 is a flow chart illustrating the operation of entities illustrated in FIG. 1.
The processes S21-S25 illustrated in FIG. 3 are similar to the processes S01-S05 illustrated in FIG. 2, and thus the content of FIG. 1 will be used for the description.
When receiving a message from the terminal A1, the CPM PF server 81B within a home network of the user B checks the status of the terminal B1 10B, and determines whether or not the transmission of the message will be deferred if the message cannot be transmitted by the terminal B1 10B (826).
When the message is deferred, the CPM PF server 81B inserts an ID of the message into a notification message indicating that the transmission of the message is deferred and then transmits it to the terminal B1 10B (S27). The terminal B1 10B stores the notification message therein (S28).
In response to the message, on the other hand, the CPM PF server 81B transmits an OK message to the CPM PF server 81A of the user A through the SIP/IP network 50B within a home network of the user B and the SIP/IP network 50A within a home network of the user A (S29-S31). The CPM PF server 81A of the user A transmits an OK message to the terminal A1 10A through the SIP/IP network 50A (S32).
On the other hand, the CPM PF server 81 B determines whether or not the message will be stored in the message storage server 60 when a timer for the deferred message is expired (S33). When it is determined to be stored, the CPM PF server 81B delivers the message to the message storage server 60 to store therein (S35, S36), and receives an OK message from the message storage server (S37). Subsequently, the CPM PF server 81B deletes the message that has been stored therein itself (S38).
On the other hand, the terminal B1 10B requests the transmission of the message to the CPM PF server 81B using an ID of the message when it becomes a state capable of receiving a message (S39).
However, because the message has been deleted in its own storage, the CPM PF server 81 B cannot process the requested transmission of the message, and as a result, it will transmit a failure message to the terminal B1 10B (S40).
In addition, there is no method for checking whether or not the message is stored within the message storage server 60, and as a result, it has a problem that the terminal B1 10B cannot acquire the message.